This invention relates to a method for producing foam, primarily utilized in a medical field and food industry, and to an apparatus for carrying out this method.
Numerous methods for making foams used in medicine and food industry are known and, typically, include porous plates traversed by a gas which runs into a foaming medical solution. Typically, the pores are distributed within the plates in an irregular manner and have different dimensions and orientations with respect to a surface of the plates. Accordingly, a velocity of jets of gas passing through pores and an angle at which these jets enter the foaming solution vary. As a consequence, a common fluid bubble, which has a diameter varying from tens of micrometers to millimeters, may be formed at a downstream end of the pores. Foams manufactured in accordance with these methods typically are not reliable and tend to break apart within a short period of time.
Examples of the discussed above methods can be found in SU, A 865295 and RU, A 2051666 disclosing a vessel for a foaming liquid which houses a sprayer provided with a perforated plate and connected to a source of gas.
Another arrangement, as disclosed in SU, A 3644304, carries out a method wherein a perforated plate is traversed by numerous jets of gas, each of which enters into a foaming composition to simultaneously form a plurality of gas bubbles.
Overall, many known arrangements utilized to carry out methods for manufacturing a foam are substantially similar to one another except for slight variations in their structures and foaming compositions, which are used for producing foam. Accordingly, foams produced by these methods typically do not have a homogeneous structure.
It is therefore an object of the invention to provide a method for manufacturing a foam having a homogeneous structure, which is characterized by substantially uniformly dimensioned and regularly spaced apart gas bubbles.
Another object of the invention is to provide a device having a porous plate, displacement of which provides substantially simultaneous separation of a plurality of the gas bubbles from pores to obtain a homogeneous structure.
This is achieved by an inventive method for producing foam wherein a gas stream is interrupted to have discreet gas portions or doses a supply rate of which and a pressure at which these portions enter a foam-forming vessel are controlled. Each of the gas portions is divided into a plurality of uniformly dimensioned components by a porous partition mounted along a path of the gas stream. Furthermore, as a plurality of evenly spaced apart uniform gas bubbles are formed on the downstream surface of the partition, the latter is controllably displaced perpendicular to the path of the gas stream to provide a supplementary sheering force sufficient to separate the bubbles from the partition between consecutive gas doses. Please replace the originally filed specification with a substitute specification enclosed herewith.
Preferably, a supply frequency varies from 20 to 100 pulses per second, whereas duration of each pulse varies from 0.001 to 0.01 sec.
Also, the gas is supplied at flow rate ranging between 0.1-5.0 l/min and under a pressure between 0.09-15.5 atm.
It is preferable to create a supplementary pull for tearing of the bubbles by reciprocally displacing a porous partition.
An apparatus having a vessel which houses a porous partition dividing the vessel into two chambers carries out the inventive method. The porous partition has a plurality of uniformly dimensioned capillary tubes forming orifices on opposite sides of the plate, which are regularly spaced from one another. The apparatus further includes a gas source in flow communication with one of the chambers by means of a pipeline and a control unit for measuring a rate and pressure of gas stream in this pipeline.
Advantageously, the partition is made from a gas impervious material; the control unit mounted in the pipeline is a valve.
Preferably, a number of capillary tubes varies from 8 to 250 per square millimeter, wherein each individual tube has a diameter ranging between 0.02 and 0.16 millimeter.
It is contemplated within the scope of this invention to have a variety of interchangeable partitions, each of which has a unique number of and dimension of the orifices.